Six-minute walk test in Chinese adults with clinically stable bronchiectasis: association with clinical indices and determinants

Background: The profiles of 6-minute walk distance (6MWD) in adults with clinically stable bronchiectasis in Chinese adult patients with bronchiectasis are unclear. Objectives: To delineate the 6MWD by stratification of clinical indices, and to investigate the factors associated with reduced 6MWD in Chinese adults with clinically stable bronchiectasis. Methods: We recruited 141 adult bronchiectasis patients (mean age: 44.3 +/- 13.9 years). Demography, radiology, spirometry, diffusing capacity, etiology, sputum bacteriology, modified Medical Research Council dyspnea scale (MMRC) and quality of life were assessed. The safety profile of the measurement was also examined. Results: Lower levels of 6MWD were associated with older age (>50 years), higher HRCT total score, presence of cystic bronchiectasis, bilateral bronchiectasis, reduced diffusing capacity, higher MMRC score, and higher SGRQ scores. Correlation coefficients between 6MWD and spirometry and quality of life scores were different in patients with 6MWD higher and lower than lower limit of normal. DLCO being less than 80% predicted (OR = 3.13, 95% CI: 1.32-7.43, P = 0.01) and MMRC scale between 1 and 4 (OR = 6.42, 95% CI: 2.27-18.18, P < 0.01) were the factors associated with 6MWD being less than the lower limit of normal (80% predicted value). No severe adverse events were reported. Conclusion: The 6MWD could be safely measured in adult patients with bronchiectasis and is poorly associated with clinical parameters. DLCO less than 80% predicted and higher MMRC scale are independent predictors of 6MWD below the lower limit of normal. Our findings will provide a reference for management of bronchiectasis patients in mainland China.